Abstract
To improve bone regeneration around orthopedic biomaterials, researchers have attempted to combine growth factors on and in implants. Equally as exciting, greater bone growth has been demonstrated around nanoscaled materials (like helical rosette nanotubes or nanocrystalline hydroxyapatite) that mimic the geometry of the natural components of bone. To combine these two approaches, in this in vitro study, the ability of three short peptides [labeled for convenience: a or SNVILKKYRN, b or KPSSAPTQLN, and c or KAISVLYFDDS chosen from the larger bone morphogenetic protein-7 (BMP-7)] to promote osteoblast (bone-forming cells) functions were determined. Shorter peptides of BMP-7 are required for growth factor incorporation into nanoscale biomaterials because their sizes are in the nanometer regime. Results showed that of all the peptides, peptide b and the peptide combination a,b, enhanced osteoblast density the most after 5 days when compared with the controls (no growth factors). Furthermore, osteoblasts cultured with peptide b had a larger and more spread morphology than did controls. In addition, peptide c and its combinations (a, c; b, c; and a, b, c) increased osteoblast calcium deposition after 14 and 21 days compared with the controls. Since these peptides are much smaller than BMP-7, the results of this study provided information that peptides can be easily chemically functionalized onto nanoscaled biomaterials to improve bone growth. Thus, the present study elucidated that shorter peptides in BMP-7 was found to be more appropriate for inclusion in and on nanomaterials to promote osteoblast proliferation (peptide b and the peptide combination a,b) and osteoblast deposition of calcium-containing mineral (peptide c and the peptide combinations a,c; b,c; and a, b, c).